Method: Polars::Functions#sql_expr

Defined in:
lib/polars/functions/lazy.rb

#sql_expr(sql) ⇒ Expr

Parse one or more SQL expressions to polars expression(s).

Examples:

Parse a single SQL expression:

df = Polars::DataFrame.new({"a" => [2, 1]})
expr = Polars.sql_expr("MAX(a)")
df.select(expr)
# =>
# shape: (1, 1)
# ┌─────┐
# │ a   │
# │ --- │
# │ i64 │
# ╞═════╡
# │ 2   │
# └─────┘

Parse multiple SQL expressions:

df.with_columns(
  *Polars.sql_expr(["POWER(a,a) AS a_a", "CAST(a AS TEXT) AS a_txt"])
)
# =>
# shape: (2, 3)
# ┌─────┬─────┬───────┐
# │ a   ┆ a_a ┆ a_txt │
# │ --- ┆ --- ┆ ---   │
# │ i64 ┆ i64 ┆ str   │
# ╞═════╪═════╪═══════╡
# │ 2   ┆ 4   ┆ 2     │
# │ 1   ┆ 1   ┆ 1     │
# └─────┴─────┴───────┘

Parameters:

  • sql (Object) —

    One or more SQL expressions.

Returns:



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# File 'lib/polars/functions/lazy.rb', line 1885

def sql_expr(sql)
  if sql.is_a?(::String)
    Utils.wrap_expr(Plr.sql_expr(sql))
  else
    sql.map { |q| Utils.wrap_expr(Plr.sql_expr(q)) }
  end
end